我的java课程有一个实验室。除了无法使普通方法正常工作外，我拥有一切。每当我运行程序时，平均值是根据随机值计算的，而不是更新的。
package ArrayKeyAccess;
/**
* Class Definition for Data Element
* Minimal Definition -- No Error Checking
* Instructional Model -- Conceptual Emphasis
*/
public class Data
{
private int studentID;
private int test1;
private int test2;
private int test3;
private int average;
private String letterGrade;
private static int nextSID = 99; //cheap sequence number approach
private static int getNextSID()
{
return ++nextSID;
}//getNextKey
public Data(int n) //no error checking
{
this.setStudentID(getNextSID());
this.setTest1(n);
this.setTest2(n);
this.setTest3(n);
}//Data constructor
public Data(int k, int n) //no uniqueness checking
{
this.setStudentID(k);
this.setTest1(n);
this.setTest2(n);
this.setTest3(n);
}//Data constructor
public Data( Data d ) //Copy Constructor
{ //required for Composition
this.setStudentID(d.getStudentID());
this.setTest1(d.getTest1());
this.setTest2(d.getTest2());
this.setTest3(d.getTest3());
this.calculateAverage(getTest1(), getTest2(), getTest3());
this.determineLetterGrade(letterGrade);
}//copy constructor
public Data copy() //Copy Object
{ //required for Compostion
return new Data(this);
}//copy object
public String toString()
{
return "Student ID: " + this.getStudentID() + '\n' +
"Test 1: " + this.getTest1() + '\n' +
"Test 2: " + this.getTest2() + '\n' +
"Test 3: " + this.getTest3() + '\n' +
"Average: " + this.getAverage() + '\n' +
"Letter Grade: " + this.getLetterGrade() + '\n';
}//toString
public void setStudentID (int n) //no error checking
{
studentID = n;
}
public int getStudentID()
{
return studentID;
}
//----------------------Test1---------------------------------------
public void setTest1(int n) //no validity checking
{
test1 = n;
}
public int getTest1()
{
return test1;
}
//----------------------Test2---------------------------------------
public void setTest2(int n) //no validity checking
{
test2 = n;
}
public int getTest2()
{
return test2;
}
//----------------------Test3---------------------------------------
public void setTest3(int n) //no validity checking
{
test3 = n;
}
public int getTest3()
{
return test3;
}
//---------------calculate average score-----------------------------
public void calculateAverage(int test1, int test2, int test3) //set
{
this.test1 = getTest1();
average = (getTest1() + getTest1() + getTest3()) / 3;
}
//----------------determine letter grade------------------------------
public void determineLetterGrade(String letterGrade)
{
if(average >= 90)
letterGrade = "A";
else if(average >= 80)
letterGrade = "B";
else if(average >= 70)
letterGrade = "C";
else if(average >= 60)
letterGrade = "D";
else
letterGrade = "F";
this.letterGrade = letterGrade;
}
//getAverageScore
public int getAverage() //get
{
return average;
}
//getLetterGrade
public String getLetterGrade()
{
return letterGrade;
}
}//class Data
ProgramTest
UnsortedArray s = new UnsortedArray(10);
int score;
//add 10 data elements
for( int i=1; i<=10; i++ )
{
score = 50 + (int)(Math.random()*50)+1;
s.insert( new Data(score) );
}
System.out.println("------------------TEST 1----------------------");
//update test 1
s.updateTest1(100,44);
s.updateTest1(101,89);
s.updateTest1(102,80);
s.updateTest1(103,95);
s.updateTest1(104,65);
s.updateTest1(105,74);
s.updateTest1(106,69);
s.updateTest1(107,56);
s.updateTest1(108,88);
s.updateTest1(109,99);
s.showList();
未排序的数组类（我以前忘了附上）
package ArrayKeyAccess;
/**
* Class Definition for Unsorted Array
* Minimal Basic Methods
* Implements Insert, Fetch, Update, Delete
* Conceptual Instructional Model
*/
public class UnsortedArray
{
private int next; //next insert position
private int size; //array capacity
private Data[] a; //reference for container of
//data elements
public UnsortedArray(int n) //no error checking
{
next = 0;
size = n;
a = new Data[size];
}//constructor
public boolean insert( Data newNode )
{
if( next >= size ) //array is full
return false;
//insert copy in next position
a[next] = new Data( newNode );
++next;
return true;
}//insert
public Data fetch( int targetKey )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return null;
else //node was found
return a[i].copy(); //return a copy
}//fetch
//Update data element field in the container
public boolean updateTest1( int targetKey, int val )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return false;
else //node was found
{
a[i].setTest1( val );
return true;
}
}//updateTest1
public boolean updateTest2( int targetKey, int val )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return false;
else //node was found
{
a[i].setTest2( val );
return true;
}
}//updateTest2
public boolean updateTest3( int targetKey, int val )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return false;
else //node was found
{
a[i].setTest3( val );
return true;
}
}//updateTest1
//overload update method
//assumes record was fetched and
//value was modified and now is
//to be "reinserted".
public boolean update( int targetKey, Data updNode )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return false;
else //node was found
{
a[i] = updNode.copy(); //assign copy
return true; //preserve Composition
}
}//update
public boolean delete( int targetKey )
{
int i=0;
while( i!=next && a[i].getStudentID()!=targetKey ) ++i;
if( i==next ) //node not found
return false;
else //node was found
{
a[i] = a[next-1]; //move last node to deleted position
//"deleted" node has no reference
a[next-1] = null; //new next available position
--next; //reset insert position
return true;
}
}//delete
public void showList() //List the nodes
{
for(int i=0; i<next; i++)
System.out.println( a[i] );
}//showList
}//class UnsortedArray
答案 0 :(得分：4)
可能是因为您添加test1两次。
average = (getTest1() + getTest1() + getTest3()) / 3;
答案 1 :(得分：4)
嗯，有两个问题。
首先，您要添加getTest1()两次。这本身就值得修复。
第二个问题是你将要进入整数除法 - 只是因为你的所有四个值都是整数，你不会得到任何浮点值（或“真正的”平均值）。
您要做的是将average的类型更改为double，然后将您的divdend更改为浮点数，如下所示：
average = (getTest1() + getTest2() + getTest3()) / 3.0;
答案 2 :(得分：0)
我想出来了，这些是我的变化，没有计算平均值或letterGrade的吸气剂
public int calculateAverage() //set
{
average = (this.getTest1() + this.getTest2() + this.getTest3()) / 3;
return average;
}
public String letterGrade()
{
if(this.average >= 90)
letterGrade = "A";
else if(this.average >= 80)
letterGrade = "B";
else if(this.average >= 70)
letterGrade = "C";
else if(this.average >= 60)
letterGrade = "D";
else
letterGrade = "F";
return letterGrade;
}
public String toString()
{
return "Student ID: " + this.getStudentID() + '\n' +
"Test 1: " + this.getTest1() + '\n' +
"Test 2: " + this.getTest2() + '\n' +
"Test 3: " + this.getTest3() + '\n' +
"Average: " + calculateAverage() + '\n' +
"Letter Grade: " + this.letterGrade() + '\n';
}//toString